All measures of body composition decreased significantly at 6 months with both groups experiencing comparable reductions in total fat mass (−5.5 [0.6] kg in the IER group vs −4.8 [0.5] kg in the CER group, diet by time P = .08) and android fat mass (−1.1 [0.2] kg in the IER group vs −0.8 [0.2] kg in the CER group, diet by time P = .16). Of note, participants in the CER group lost significantly more total fat-free mass than did participants in the IER group (mean [SEM], −2.3 [0.2] kg vs −1.7 [0.2] kg; P = .03], and there was a trend toward a greater change in total fat mass in the IER group (P = .08). The secondary outcome of mean (SEM) HbA1c (−0.2% [0.1%]) and blood lipid levels (triglyceride level, −1.0 [0.3] mmol/L; total cholesterol level, −0.9 [0.2] mmol/L; low-density lipoprotein cholesterol level, −0.9 [0.2 mmol/L; high-density lipoprotein cholesterol level, 0.7 [0.3] mmol/L] improved with weight loss (P < .05), with no differences between groups (diet by time P > .05).
The intention-to-treat analysis demonstrated that IER and CER are equally effective for weight loss and blood pressure control: both groups experienced significant reductions in weight, SBP, and DBP, but with no difference between treatment groups – mean (SEM) weight change with IER was −7.0 (0.6) kg vs −6.8 (0.6) kg with CER; the mean (SEM) SBP with IER was −7 (0.7) mmHg vs −7 (0.6) mmHg with CER; and the mean (SEM) DBP with IER was −6 (0.5) mmHg vs −5 (0.5) mmHg with CER, (diet by time P = .62, .39, and .41, respectively). There were favorable improvements in body composition, HbA1c, and blood lipid levels, with no differences between groups.
Conclusion. A 2-day severe energy restriction with 5 days of habitual eating compared to 7 days of CER provides an acceptable alternative for BP control and weight loss in overweight and obese individuals with hypertension after 6 months. IER may offer a useful alternative strategy for this population, who find continuous weight-loss diets too difficult to maintain.
Commentary
Globally, obesity represents a major health challenge as it substantially increases the risk of diseases such as hypertension, type 2 diabetes, and coronary heart disease.1 Lifestyle modifications, including weight loss and increased physical activity, are recommended in major guidelines as a first-step intervention in the treatment of hypertensive patients.2 However, lifestyle and behavioral interventions aimed at reducing calorie intake through low-calorie dieting is challenging as it is dependent on individual motivation and adherence to a strict, continuous protocol. Further, CER strategies have limited effectiveness because complex and persistent hormonal, metabolic, and neurochemical adaptations defend against weight loss and promote weight regain.3-4 IER has drawn attention in the popular media as an alternative to CER due to its feasibility and even potential for higher rates of compliance.5
This study adds to the literature as it is the first randomized controlled trial (to the knowledge of the authors at the time of publication) to explore 2 forms of energy restriction – CER and IER – and their impact on weight loss, BP, body composition, HbA1c, and blood lipid levels in overweight and obese patients with high blood pressure. Results from this study showed that IER is as effective as, but not superior to, CER (in terms of the outcomes measures assessed). Specifically, findings highlighted that the 5:2 diet is an effective strategy and noninferior to that of daily calorie restriction for BP and weight control. In addition, both weight loss and BP reduction were greater in a subgroup of obese compared with overweight participants, which indicates that obese populations may benefit more from energy restriction. As the authors highlight, this study both aligns with and expands on current related literature.